@CaptainJustice, one thing I have started doing is simply keeping all my files in just a few huge-ass directories on my computer. All the files are sync'd to other machines via Nextcloud or Box.
Then I simply drag them into my plex whenever I need them in a thought, and they get represented as a link/shortcut to the file on my drive.
Of course, you lose the context of the plex when you're exploring the files via Finder/Explorer. But it helps me a bit to have my files available to be easily sync'd and available to other applications on other machines.